Microwaves readily pass through many materials, such as glass, most plastics, paper and china, with little or no effect.

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Hence to protect the user from the radiation of the microwave while operating, it is usually made of specific materials.

The door has a window with a perforated (having small holes) metal shield that enables the user to view the food while it is cooking. The microwaves cannot go through

the holes to cause any harm as the holes are smaller than the wavelengths of the microwaves.


The outer covering of a microwave oven is usually a one-piece sheet metal enclosure. The door and the panels of the cooking cavity are made of stainless steel or

galvanized steel (steel that has been coated with a thin layer of zinc to protect against rusting). These panel of steel would serve as a deflector for the radiation created by

microwaves as microwaves cannot penetrate steel.